After President Trump continued to make false claims about Amazon last week — including that it doesn't collect enough state and local sales tax — it emerged that Trump's online store only collects sales tax in two states. Amazon does so in 45.

Trumpstore.com, the official online store of the Trump Organization, only collects sales tax on orders shipped to Louisiana and Florida, the "Wall Street Journal" reported. When Amazon launched, it only collected sales taxes in five states. But now it does so in every state where sales tax exists.

What is Trump's beef with Amazon?

Trump has repeatedly hammered Amazon and its owner, Jeff Bezos, attacks which many say are politically motivated. Bezos also owns the "Washington Post," which has angered Trump by publishing stories critical about his presidency and presidential campaign. At one point, Trump banned the "Post" from his campaign events. In angry tweets, Trump has conflated the two companies, calling it "AmazonWashingtonPost." The companies operate independently.

Trump's business says their sales-tax policy is above board. "Trumpstore.com has always, and will continue to collect, report, and remit sales taxes in jurisdictions where it has an obligation to do so," a Trump Organization spokesperson told CNBC.

And that's true: Online retailers are required to collect sales tax only in states where they have a physical presence. After the Trump administration filed a brief last month, the Supreme Court will hear a challenge to that law this spring.

Trump has also tweeted accusations that Amazon exploits the U.S. Postal Service, which is contracted to deliver its packages. "While we are on the subject, it is reported that the U.S. Post Office will lose $1.50 on average for each package it delivers for Amazon. That amounts to Billions of Dollars," Trump tweeted.

That is untrue. Delivering packages for Amazon is actually profitable for the Postal Service at a time when snail mail delivery continues to plummet.

Last week it was reported that the Trump spent more than $150,000 on Amazon in 379 transactions during 2015 and 2016. The campaign spent more than $2,000 in 2017.